Added other option to picks and grids.

User can enter "other" checkbox and receive a spot
to create their own answer choice.
	modified:   app/models/permitted_params_decorator.rb - added other
	and other_text

	modified:   app/views/questions/_answer_fields.html.erb - added other
	checkbox and other_text to pick question builder.

	modified:   app/views/questions/_grid_fields.html.erb - added other
	checkbox and other_text to grid question builder.

	modified:   app/views/surveyforms/_question_field.html.erb - added
	other text box next to radio and checkboxes.

	modified:   lib/assets/stylesheets/surveyor_gui/surveyor_gui.sass

	modified:   lib/surveyor_gui/models/question_methods.rb - added other
	to _build_custom_question_structure.

	modified:   lib/surveyor_gui/models/question_type_methods.rb - added other
	and other text to grid builders and answer builders.